The capability of making emergency calls are typically an element of most systems that assist the elderly. These types of emergency call systems are similar to nurse call systems in a hospital or skilled environment and are found in residential settings, which could be either single family or a community of independent living or assisted living residences. An emergency call is placed by a resident and used to summon assistance.
Usually an emergency call system includes an initiator, some type of communication system, a processor and display. These systems can broadly be classified as hard-wired, telephony or wireless, depending on the type of initiator or communication system. An example of an emergency call system that incorporates all three systems is disclosed in U.S. Pat. Nos. 6,646,549; 6,765,992; and 6,870,906, the disclosures which are hereby incorporated by reference in their entirety.
Traditional emergency call systems have typically used an initiator, having one or more call cords or other fixed devices for operation by the resident. This type of device creates a contact closure or other closed circuit for activating the emergency call. The requirement for emergency assistance is communicated using a communications system to the processor, and displayed on a display for viewing by an attendant. Any caregiver, noting the call on the display, knows that a resident requiring assistance is located at one of the devices in that residence.
In some cases, a fixed initiator is replaced with a portable, typically short range RF signal, emergency call transmitter worn by the resident, for example, a wireless pendant. The emergency call transmitter transmits an RF signal that incorporates a unique transmitter code, which is used by the processor to identify the resident. There are usually one or more compatible emergency call receivers capable of receiving a transmission from the emergency call transmitter and initiating an emergency call to a caregiver. The resident can be anywhere within their residence, whether a single family home or an apartment in a community, and can summon help without having to be at a fixed location. This combination of an emergency call transmitter and emergency call receiver typically constitutes an initiator in some emergency call systems.
The communication system that forwards the help signal to a processor at an attended location is not limited to one system, but typically could be one of three different systems: (1) using wires extending to central equipment (hard-wired); (2) using the public switched telephone network (PSTN) to make a connection to the central equipment (telephony); or (3) using an RF data circuit. In some systems, hard-wired systems typically have fixed initiators and hard-wired communication systems, while telephony systems use both fixed and wireless initiators and telephony communication systems. Wireless systems typically use a wireless initiator and either hard-wired or wireless communication systems. Different examples are set forth in the incorporated by reference '549, '992 and '906 patents.
The processor and display could be located at the assisted living or independent living community, or in the case of single family residences, could be located at a geographically remote location. The display could be a computer screen, textual or graphic enunciator, pocket pager, cell phone screen or PDA.
Usually when a fixed initiator is used, a caregiver knows that the resident is located near one of the fixed devices in an apartment or single family residence. With a wireless initiator, however, the resident could be located within the coverage area covered by the emergency call transmitter and emergency call receiver. For example, in an independent living or assisted living community, the resident could be anywhere within the building. In a single family residence, the resident could be in any room of the residence.
There have been several techniques to determine a more precise location of a monitored resident during an emergency when using a wireless system. For example, the processor could identify the locations of one or more of the emergency call receivers that receive an RF signal from an emergency call transmitter. A display could list those locations, or present a graphic indicating the likely area in which the resident is located, based on the received locations. If the relative RF signal strength at each emergency call receiver is known, that information could be used to refine the likely area in which the resident that activated the emergency call is located.
These systems have not always been feasible because the RF signals propagate within a structure, and are subject to attenuation as the RF signal passes through walls and floors. The RF signals are also subject to reflection as the signals encounter various surfaces. These reflections cause the signal to traverse the distance from a transmitter to a receiver over many different paths creating multipath delays. Because each path has a different length than the other paths, the phases of the signals arriving via the multiple paths will vary. As signals of various phases are combined at the receiving antenna, the resulting signal strength is, in the aggregate, typically much more or much less than would be encountered in a reflection free environment. This “multipath fading” is well known and can create an ineffective emergency call system. This type of system will also have a similar effect on more complex attempts using time-based ranging. Also, the passage of RF signals through floors further complicates the location attempt in three-dimensional space.
As noted above, wireless emergency call systems typically use wireless emergency call transmitters, for example, wireless pendants that are formed as short range RF transmitters. Besides emergency call systems, other short range RF transmitters are used in a variety of applications from garage door openers to keyless entry systems for automobiles and homes, as well as the emergency call systems for the elderly as discussed. A short range RF transmitter, for example, an emergency call transmitter, contains a unique code identifying a particular transmitter to a receiver. In some devices, the code had been set by a mechanical system, for example, “DIP switches.” In that system, both the transmitter and receiver would include DIP switches, and the DIP switches in both systems would be set to the same code, allowing the receiver to perform a desired output when a matching code is received from the transmitter. In other cases, a receiver determined a code to which it should respond, or sometimes the receiver responded to several different codes, each producing a different result.
Mechanical DIP switches are not favored because they are expensive, compared to the overall cost of the transmitter, and also require a manufacturer or user to open the case or housing for access, ruling out a substantially waterproof transmitter. Also, DIP switches can be set incorrectly, resulting in failure of the entire system.
Typically, modern short range RF transmitters used as emergency call transmitters are given permanent codes when they are manufactured. The code is incorporated into the programming of the device, or set in a permanent memory, such as an EEPROM. In some cases, the receiver is “taught” the code by performing a specified sequence that includes activating the short range RF transmitter in the presence of the receiver. In still other cases, the receiver may receive all codes and forward them to other equipment, which will recognize and interpret the code. In other cases, special equipment programs the code into the receiver. In any event, replacement of these short range RF transmitters, such as emergency call transmitters, is a labor intensive operation. Supplying a short range RF transmitter with a given code is impractical, particularly when tens or hundreds of thousands or more of different codes exist. Stocking several of each code for replacement purposes is cost prohibitive, while manufacturing custom codes to order is impractical.
One well established alternative has been to program the short range RF transmitter after it is manufactured through an appropriate connector that is connected to a special programmer. This type of system is low cost and quick, but cannot be used with a short range RF transmitter that has been permanently sealed, for example, for waterproofing, because its enclosure cannot be opened without destroying the device.